Add origin flag for so files

[mls-m5]

When linking so-files and outputting in another folder you need to add a flag $ORIGIN-something to make the application look for files in the applicatitons directory.

[mls-m5]

Check here for how it is done in matmake2

Hints

-l:libname.so -L path/to/lib -Wl,-rpath='$$ORIGIN'

Double $ to avoid ninja or makefile from removing one of them. Might be better fixed some other way.

The problem is how to solve what is called "linkstring" in matmake v1